What's important to consider when buying a keyboard?

What's important to consider when buying a keyboard?
(*) This question was posed to Juan María Solare by a journalist who prefered to hide his or her identity.

I am writing here as a professional pianist with 400+ concerts on my account and over 30 years since my first public gig.
Certainly, most of my concerts are on a "real" grand piano - but I also play a part of my recitals with a keyboard (or a stage piano). If not, both my musical career and my pocket would suffer.

What is important to consider when buying a keyboard?

In the end you must find a balance (let's face it: a compromise) between price, weight, sound quality, versatility / functionality, intuitiveness of use and "feeling" (i.e. whether it feels like a real piano or not).

Since the answers depend on your needs, you should... you MUST write down several questions before even going to a store. Questions as elemental as:

* Can I use a car to transport my keyboard? (if not, the weight of the creature is a decisive issue)

* Do I need built-in loudspeakers or there are external ones (at least a portable amplifier)?

* Do I need / want lots of fancy sounds or just -say- five excellent piano sounds?

* Am I short of money, can I re-finance the instrument with a couple of gigs?

* Are the functions relatively easy to find, are they where you would spontaneously look for them? If you need 15 seconds to change an elemental setting hidden in some menu, this might not be practical on stage - except that you are satisfied with one setting for the whole song or even for the whole concert.

* Which connections are essential? Audio, MIDI, possibly USB... will I connect my keyboard to my tablet or smartphone (iPhone or iPad) instead of a laptop?

* Do I need the standard 88 keys or are 49 more than enough for my goals?

I personally give extreme importance to the feeling of the keys. If this is important or you, try testing weighted keys (usually wooden ones), but remember that thus your keyboard will be much heavier. This is one of the few aspects you cannot test online.

It might be that -being sincere to yourself- you still cannot answer to that questions. In this case my best advice is: purchase or rent the cheapest keyboard you can get (the cheapest that gets the job done!) in order to learn exactly what you need. If after a couple of gigs you are still unsure what do you need, it means your provisional decision was not that bad.